Flow control in subterranean wells

ABSTRACT

A method of controlling flow in a well can include a device introduced into the well being conveyed by flow in the well, and the device having a plurality of fibers extending outwardly from a body. A well system can include a flow conveyed device conveyed through a tubular string by flow in the tubular string, and the flow conveyed device including a body with a plurality of fibers extending outwardly from the body. A flow conveyed device for use in a well can include a degradable body, and a plurality of fibers joined to the body, each of the fibers having a lateral dimension that is substantially smaller than a size of the body.

BACKGROUND

This disclosure relates generally to equipment utilized and operationsperformed in conjunction with a subterranean well and, in one exampledescribed below, more particularly provides for flow control in wells.

It can be beneficial to be able to control how and where fluid flows ina well. For example, it may be desirable in some circumstances to beable to prevent fluid from flowing into a particular formation zone. Asanother example, it may be desirable in some circumstances to causefluid to flow into a particular formation zone, instead of into anotherformation zone. Therefore, it will be readily appreciated thatimprovements are continually needed in the art of controlling fluid flowin wells.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representative partially cross-sectional view of an exampleof a well system and associated method which can embody principles ofthis disclosure.

FIGS. 2A-D are enlarged scale representative partially cross-sectionalviews of steps in an example of a re-completion method that may bepracticed with the system of FIG. 1.

FIGS. 3A-D are representative partially cross-sectional views of stepsin another example of a method that may be practiced with the system ofFIG. 1.

FIG. 4 is an enlarged scale representative elevational view of a flowconveyed device that may be used in the system and methods of FIGS.1-3D, and which can embody the principles of this disclosure.

FIG. 5 is a representative elevational view of another example of theflow conveyed device.

FIGS. 6A & B are representative partially cross-sectional views of theflow conveyed device in a well, the device being conveyed by flow inFIG. 6A, and engaging a casing opening in FIG. 6B.

DETAILED DESCRIPTION

Representatively illustrated in FIG. 1 is a system 10 for use with awell, and an associated method, which can embody principles of thisdisclosure. However, it should be clearly understood that the system 10and method are merely one example of an application of the principles ofthis disclosure in practice, and a wide variety of other examples arepossible. Therefore, the scope of this disclosure is not limited at allto the details of the system 10 and method described herein and/ordepicted in the drawings.

In the FIG. 1 example, a tubular string 12 is conveyed into a wellbore14 lined with casing 16 and cement 18. Although multiple casing stringswould typically be used in actual practice, for clarity of illustrationonly one casing string 16 is depicted in the drawings.

Although the wellbore 14 is illustrated as being vertical, sections ofthe wellbore could instead be horizontal or otherwise inclined relativeto vertical. Although the wellbore 14 is completely cased and cementedas depicted in FIG. 1, any sections of the wellbore in which operationsdescribed in more detail below are performed could be uncased or openhole. Thus, the scope of this disclosure is not limited to anyparticular details of the system 10 and method.

The tubular string 12 of FIG. 1 comprises coiled tubing 20 and a bottomhole assembly 22. As used herein, the term “coiled tubing” refers to asubstantially continuous tubing that is stored on a spool or reel 24.The reel 24 could be mounted, for example, on a skid, a trailer, afloating vessel, a vehicle, etc., for transport to a wellsite. Althoughnot shown in FIG. 1, a control room or cab would typically be providedwith instrumentation, computers, controllers, recorders, etc., forcontrolling equipment such as an injector 26 and a blowout preventerstack 28.

As used herein, the term “bottom hole assembly” refers to an assemblyconnected at a distal end of a tubular string in a well. It is notnecessary for a bottom hole assembly to be positioned or used at a“bottom” of a hole or well.

When the tubular string 12 is positioned in the wellbore 14, an annulus30 is formed radially between them. Fluid, slurries, etc., can be flowedfrom surface into the annulus 30 via, for example, a casing valve 32.One or more pumps 34 may be used for this purpose. Fluid can also beflowed to surface from the wellbore 14 via the annulus 30 and valve 32.

Fluid, slurries, etc., can also be flowed from surface into the wellbore14 via the tubing 20, for example, using one or more pumps 36. Fluid canalso be flowed to surface from the wellbore 14 via the tubing 20.

In the further description below of the examples of FIGS. 2A-6B, one ormore flow conveyed devices are used to block or plug openings in thesystem 10 of FIG. 1. However, it should be clearly understood that thesemethods and the flow conveyed device may be used with other systems, andthe flow conveyed device may be used in other methods in keeping withthe principles of this disclosure.

The example methods described below allow existing fluid passageways tobe blocked permanently or temporarily in a variety of differentapplications. Flow conveyed device examples described below are made ofa fibrous material and comprise a “knot” or other enlarged geometry.

The devices are conveyed into leak paths using pumped fluid. The fibrousmaterial “finds” and follows the fluid flow, pulling the enlargedgeometry into a restricted portion of a flow path, causing the enlargedgeometry and additional strands to become tightly wedged into the flowpath thereby sealing off fluid communication.

The devices can be made of degradable or non-degradable materials. Thedegradable materials can be either self-degrading, or can requiredegrading treatments, such as, by exposing the materials to certainacids, certain base compositions, certain chemicals, certain types ofradiation (e.g., electromagnetic or “nuclear”), or elevated temperature.The exposure can be performed at a desired time using a form of wellintervention, such as, by spotting or circulating a fluid in the well sothat the material is exposed to the fluid.

In some examples, the material can be an acid degradable material (e.g.,nylon, etc.), a mix of acid degradable material (for example, nylonfibers mixed with particulate such as calcium carbonate), self-degradingmaterial (e.g., poly-lactic acid (PLA), poly-glycolic acid (PGA), etc.),material that degrades by galvanic action (such as, magnesium alloys,aluminum alloys, etc.), a combination of different self-degradingmaterials, or a combination of self-degrading and non-self-degradingmaterials.

Multiple materials can be pumped together or separately. For example,nylon and calcium carbonate could be pumped as a mixture, or the nyloncould be pumped first to initiate a seal, followed by calcium carbonateto enhance the seal.

In certain examples described below, the device can be made of knottedfibrous materials. Multiple knots can be used with any number of looseends. The ends can be frayed or un-frayed. The fibrous material can berope, fabric, cloth or another woven or braided structure.

The device can be used to block open sleeve valves, perforations or anyleak paths in a well (such as, leaking connections in casing, corrosionholes, etc.). Any opening through which fluid flows can be blocked witha suitably configured device.

In one example method described below, a well with an existingperforated zone can be re-completed. Devices (either degradable ornon-degradable) are conveyed by flow to plug all existing perforations.

The well can then be re-completed using any desired completiontechnique. If the devices are degradable, a degrading treatment can thenbe placed in the well to open up the plugged perforations (if desired).

In another example method described below, multiple formation zones canbe perforated and fractured in a single trip of the bottom hole assembly22 into the well. In the method, one zone is perforated, the zone isfractured, and then the perforated zone is plugged using one or moredevices.

These steps are repeated for each additional zone, except that a lastzone is not plugged. All of the plugged zones are eventually unpluggedby waiting a certain period of time (if the devices are self-degrading),or by applying an appropriate degrading treatment.

Referring specifically now to FIGS. 2A-D, steps in an example of amethod in which the bottom hole assembly 22 of FIG. 1 can be used inre-completing a well are representatively illustrated. In this method(see FIG. 2A), the well has existing perforations 38 that provide forfluid communication between an earth formation zone 40 and an interiorof the casing 16. However, it is desired to re-complete the zone 40, inorder to enhance the fluid communication.

Referring additionally now to FIG. 2B, the perforations 38 are plugged,thereby preventing flow through the perforations into the zone 40. Plugs42 in the perforations can be flow conveyed devices, as described morefully below. In that case, the plugs 42 can be conveyed through thecasing 16 and into engagement with the perforations 38 by fluid flow 44.

Referring additionally now to FIG. 2C, new perforations 46 are formedthrough the casing 16 and cement 18 by use of an abrasive jet perforator48. In this example, the bottom hole assembly 22 includes the perforator48 and a circulating valve assembly 50. Although the new perforations 46are depicted as being formed above the existing perforations 38, the newperforations could be formed in any location in keeping with theprinciples of this disclosure.

Note that other means of providing perforations 46 may be used in otherexamples. Explosive perforators, drills, etc., may be used if desired.The scope of this disclosure is not limited to any particularperforating means, or to use with perforating at all.

The circulating valve assembly 50 controls flow between the coiledtubing 20 and the perforator 48, and controls flow between the annulus30 and an interior of the tubular string 12. Instead of conveying theplugs 42 into the well via flow 44 through the interior of the casing 16(see FIG. 2B), in other examples the plugs could be deployed into thetubular string 12 and conveyed by fluid flow 52 through the tubularstring prior to the perforating operation. In that case, a valve 54 ofthe circulating valve assembly 50 could be opened to allow the plugs 42to exit the tubular string 12 and flow into the interior of the casing16 external to the tubular string.

Referring additionally now to FIG. 2D, the zone 40 has been fractured byapplying increased pressure to the zone after the perforating operation.Enhanced fluid communication is now permitted between the zone 40 andthe interior of the casing 16. Note that fracturing is not necessary inkeeping with the principles of this disclosure.

In the FIG. 2D example, the plugs 42 prevent the pressure applied tofracture the zone 40 via the perforations 46 from leaking into the zonevia the perforations 38. The plugs 42 may remain in the perforations 38and continue to prevent flow through the perforations, or the plugs maydegrade, if desired, so that flow is eventually permitted through theperforations.

Referring additionally now to FIGS. 3A-D, steps in another example of amethod in which the bottom hole assembly 22 of FIG. 1 can be used incompleting multiple zones 40 a-c of a well are representativelyillustrated. The multiple zones 40 a-c are each perforated and fracturedduring a single trip of the tubular string 12 into the well.

In FIG. 3A, the tubular string 12 has been deployed into the casing 16,and has been positioned so that the perforator 48 is at the first zone40 a to be completed. The perforator 48 is then used to formperforations 46 a through the casing 16 and cement 18, and into the zone40 a.

In FIG. 3B, the zone 40 a has been fractured by applying increasedpressure to the zone via the perforations 46 a. The fracturing pressuremay be applied, for example, via the annulus 30 from the surface (e.g.,using the pump 34 of FIG. 1), or via the tubular string 12 (e.g., usingthe pump 36 of FIG. 1). The scope of this disclosure is not limited toany particular fracturing means or technique, or to the use offracturing at all.

After fracturing of the zone 40 a, the perforations 46 a are plugged bydeploying plugs 42 a into the well and conveying them by fluid flow intosealing engagement with the perforations. The plugs 42 a may be conveyedby flow 44 through the casing 16 (e.g., as in FIG. 2B), or by flow 52through the tubular string 12 (e.g., as in FIG. 2C).

The tubular string 12 is repositioned in the casing 16, so that theperforator 48 is now located at the next zone 40 b to be completed. Theperforator 48 is then used to form perforations 46 b through the casing16 and cement 18, and into the zone 40 b. The tubular string 12 may berepositioned before or after the plugs 42 a are deployed into the well.

In FIG. 3C, the zone 40 b has been fractured by applying increasedpressure to the zone via the perforations 46 b. The fracturing pressuremay be applied, for example, via the annulus 30 from the surface (e.g.,using the pump 34 of FIG. 1), or via the tubular string 12 (e.g., usingthe pump 36 of FIG. 1).

After fracturing of the zone 40 b, the perforations 46 b are plugged bydeploying plugs 42 b into the well and conveying them by fluid flow intosealing engagement with the perforations. The plugs 42 b may be conveyedby flow 44 through the casing 16, or by flow 52 through the tubularstring 12.

The tubular string 12 is repositioned in the casing 16, so that theperforator 48 is now located at the next zone 40 c to be completed. Theperforator 48 is then used to form perforations 46 c through the casing16 and cement 18, and into the zone 40 c. The tubular string 12 may berepositioned before or after the plugs 42 b are deployed into the well.

In FIG. 3D, the zone 40 c has been fractured by applying increasedpressure to the zone via the perforations 46 c. The fracturing pressuremay be applied, for example, via the annulus 30 from the surface (e.g.,using the pump 34 of FIG. 1), or via the tubular string 12 (e.g., usingthe pump 36 of FIG. 1).

The plugs 42 a,b are degraded and no longer prevent flow through theperforations 46 a,b. Thus, as depicted in FIG. 3D, flow is permittedbetween the interior of the casing 16 and each of the zones 40 a-c.

The plugs 42 a,b may be degraded in any manner. The plugs 42 a,b maydegrade in response to application of a degrading treatment, in responseto passage of a certain period of time, or in response to exposure toelevated downhole temperature. The degrading treatment could includeexposing the plugs 42 a,b to a particular type of radiation, such aselectromagnetic radiation (e.g., light having a certain wavelength orrange of wavelengths, gamma rays, etc.) or “nuclear” particles (e.g.,gamma, beta, alpha or neutron).

The plugs 42 a,b may degrade by galvanic action or by dissolving. Theplugs 42 a,b may degrade in response to exposure to a particular fluid,either naturally occurring in the well (such as water or hydrocarbonfluid), or introduced therein.

Note that any number of zones may be completed in any order in keepingwith the principles of this disclosure. The zones 40 a-c may be sectionsof a single earth formation, or they may be sections of separateformations.

Referring additionally now to FIG. 4, an example of a flow conveyeddevice 60 that can incorporate the principles of this disclosure isrepresentatively illustrated. The device 60 may be used for any of theplugs 42, 42 a,b described above in the method examples of FIGS. 2A-3D,or the device may be used in other methods.

The device 60 example of FIG. 4 includes multiple fibers 62 extendingoutwardly from an enlarged body 64. As depicted in FIG. 4, each of thefibers 62 has a lateral dimension (e.g., a thickness or diameter) thatis substantially smaller than a size (e.g., a thickness or diameter) ofthe body 64.

The body 64 can be dimensioned so that it will effectively engage andseal off a particular opening in a well. For example, if it is desiredfor the device 60 to seal off a perforation in a well, the body 64 canbe formed so that it is somewhat larger than a diameter of theperforation. If it is desired for multiple devices 60 to seal offmultiple openings having a variety of dimensions (such as holes causedby corrosion of the casing 16), then the bodies 64 of the devices can beformed with a corresponding variety of sizes.

In the FIG. 4 example, the fibers 62 are joined together (e.g., bybraiding, weaving, cabling, etc.) to form lines 66 that extend outwardlyfrom the body 64. In this example, there are two such lines 66, but anynumber of lines (including one) may be used in other examples.

The lines 66 may be in the form of one or more ropes, in which case thefibers 62 could comprise frayed ends of the rope(s). In addition, thebody 64 could be formed by one or more knots in the rope(s). In someexamples, the body 64 can comprise a fabric or cloth, the body could beformed by one or more knots in the fabric or cloth, and the fibers 62could extend from the fabric or cloth.

In the FIG. 4 example, the body 64 is formed by a double overhand knotin a rope, and ends of the rope are frayed, so that the fibers 62 aresplayed outward. In this manner, the fibers 62 will cause significantfluid drag when the device 60 is deployed into a flow stream, so thatthe device will be effectively “carried” by, and “follow,” the flow.

However, it should be clearly understood that other types of bodies andother types of fibers may be used in other examples. The body 64 couldhave other shapes, the body could be hollow or solid, and the body couldbe made up of one or multiple materials. The fibers 62 are notnecessarily joined by lines 66, and the fibers are not necessarilyformed by fraying ends of ropes or other lines. Thus, the scope of thisdisclosure is not limited to the construction, configuration or otherdetails of the device 60 as described herein or depicted in thedrawings.

Referring additionally now to FIG. 5, another example of the device 60is representatively illustrated. In this example, four sets of thefibers 62 are joined by a corresponding number of lines 66 to the body64. The body 64 is formed by one or more knots in the lines 66.

FIG. 5 demonstrates that a variety of different configurations arepossible for the device 60. Accordingly, the principles of thisdisclosure can be incorporated into other configurations notspecifically described herein or depicted in the drawings. Such otherconfigurations may include fibers joined to bodies without use of lines,bodies formed by techniques other than knotting, etc.

Referring additionally now to FIGS. 6A & B, an example of a use of thedevice 60 of FIG. 4 to seal off an opening 68 in a well isrepresentatively illustrated. In this example, the opening 68 is aperforation formed through a sidewall 70 of a tubular string 72 (suchas, a casing, liner, tubing, etc.). However, in other examples theopening 68 could be another type of opening, and may be formed inanother type of structure.

The device 60 is deployed into the tubular string 72 and is conveyedthrough the tubular string by fluid flow 74. The fibers 62 of the device60 enhance fluid drag on the device, so that the device is influenced todisplace with the flow 74.

Since the flow 74 (or a portion thereof) exits the tubular string 72 viathe opening 68, the device 60 will be influenced by the fluid drag toalso exit the tubular string via the opening 68. As depicted in FIG. 6B,one set of the fibers 62 first enters the opening 68, and the body 64follows. However, the body 64 is appropriately dimensioned, so that itdoes not pass through the opening 68, but instead is lodged or wedgedinto the opening. In some examples, the body 64 may be received onlypartially in the opening 68, and in other examples the body may beentirely received in the opening.

The body 64 may completely or only partially block the flow 74 throughthe opening 68. If the body 64 only partially blocks the flow 74, anyremaining fibers 62 exposed to the flow in the tubular string 72 can becarried by that flow into any gaps between the body and the opening 68,so that a combination of the body and the fibers completely blocks flowthrough the opening.

In another example, the device 60 may partially block flow through theopening 68, and another material (such as, calcium carbonate, PLA or PGAparticles) may be deployed and conveyed by the flow 74 into any gapsbetween the device and the opening, so that a combination of the deviceand the material completely blocks flow through the opening.

The device 60 may permanently prevent flow through the opening 68, orthe device may degrade to eventually permit flow through the opening. Ifthe device 60 degrades, it may be self-degrading, or it may be degradedin response to any of a variety of different stimuli. Any technique ormeans for degrading the device 60 (and any other material used inconjunction with the device to block flow through the opening 68) may beused in keeping with the scope of this disclosure.

It may now be fully appreciated that the above disclosure providessignificant advancements to the art of controlling flow in subterraneanwells. In some examples described above, the device 60 may be used toblock flow through openings in a well, with the device being uniquelyconfigured so that its conveyance with the flow is enhanced.

The above disclosure provides to the art a method of controlling flow ina subterranean well. In one example, the method can comprise: a device60 introduced into the well being conveyed by flow 74 in the well, andthe device 60 comprising a plurality of fibers 62 extending outwardlyfrom a body 64.

The method can include the body 64 engaging an opening 68 in the well.The opening 68 may comprise a perforation. In other examples, theopening 68 could be in a valve, at a corrosion location, a point ofleakage, etc. The body 64 can prevent flow through the opening 68.

The fibers 62 may be joined together and form one or more lines 66extending outwardly from the body 64. The lines 66 can comprise one ormore ropes. The body 64 can comprise a fabric or cloth.

The body 64 can comprise at least one knot. Other structures (such as,spheres, oblong structures, etc.) may be used in other examples.

The body 64 can comprise a non-degradable or a degradable material. Thebody 64 may be self-degrading, or the body may degrade in response toapplication of a degrading treatment. The method can include thematerial degrading in response to at least one of: passage of apredetermined period of time in the well, exposure to a predeterminedtemperature in the well, exposure to a predetermined fluid in the well,exposure to radiation (e.g., electromagnetic, light or nuclear, such asgamma, beta, alpha or neutron particles), and exposure to apredetermined chemical composition in the well.

The method can include deploying the device 60 into the well afterfracturing a formation zone 40 a,b. The device 60 may be deployed, andthe formation zone 40 a,b may be fractured, during a single trip of atubular string 12 into a well.

As used herein, the term “single trip” is used to indicate only a singledeployment of a tubular string into a well. The tubular string may beretrieved from the well at a conclusion of the single trip, or thetubular string may not be retrieved from the well.

Also provided to the art by the above disclosure is a system 10 for usewith a well. In one example, the system 10 can comprise a flow conveyeddevice 60 conveyed through a tubular string 72 by flow 74 in the tubularstring. The flow conveyed device 60 can comprise a body 64 with aplurality of fibers 62 extending outwardly from the body.

The flow conveyed device 60 may engage an opening 68 in a sidewall 70 ofthe tubular string 72. At least a portion of the fibers 62 can beconveyed into the opening 68 by flow 74 through the opening.

The body 64 may extend across and seal off the opening 68. The opening68 can comprise a perforation. The scope of this disclosure is notlimited to any particular type of opening.

A flow conveyed device 60 for use in a subterranean well is alsodescribed above. In one example, the device 60 can comprise a degradablebody 64, and a plurality of fibers 62 joined to the body. Each of thefibers 62 has a lateral dimension that is substantially smaller than asize of the body 64.

The body 64 may degrade in response to passage of a predetermined periodof time, exposure to a predetermined fluid, exposure to a predeterminedchemical composition, exposure to radiation (e.g., electromagnetic,light or nuclear, such as gamma, beta, alpha or neutron particles),and/or exposure to a predetermined temperature. In some examples, thebody 64 may not be degradable.

The fibers 62 may comprise a nylon material. The fibers 62 can extendfrom one or more ropes, fabrics or cloths in some examples.

The body 64 may be degradable by exposure to an acid.

Although various examples have been described above, with each examplehaving certain features, it should be understood that it is notnecessary for a particular feature of one example to be used exclusivelywith that example. Instead, any of the features described above and/ordepicted in the drawings can be combined with any of the examples, inaddition to or in substitution for any of the other features of thoseexamples. One example's features are not mutually exclusive to anotherexample's features. Instead, the scope of this disclosure encompassesany combination of any of the features.

Although each example described above includes a certain combination offeatures, it should be understood that it is not necessary for allfeatures of an example to be used. Instead, any of the featuresdescribed above can be used, without any other particular feature orfeatures also being used.

It should be understood that the various embodiments described hereinmay be utilized in various orientations, such as inclined, inverted,horizontal, vertical, etc., and in various configurations, withoutdeparting from the principles of this disclosure. The embodiments aredescribed merely as examples of useful applications of the principles ofthe disclosure, which is not limited to any specific details of theseembodiments.

In the above description of the representative examples, directionalterms (such as “above,” “below,” “upper,” “lower,” etc.) are used forconvenience in referring to the accompanying drawings. However, itshould be clearly understood that the scope of this disclosure is notlimited to any particular directions described herein.

The terms “including,” “includes,” “comprising,” “comprises,” andsimilar terms are used in a non-limiting sense in this specification.For example, if a system, method, apparatus, device, etc., is describedas “including” a certain feature or element, the system, method,apparatus, device, etc., can include that feature or element, and canalso include other features or elements. Similarly, the term “comprises”is considered to mean “comprises, but is not limited to.”

Of course, a person skilled in the art would, upon a carefulconsideration of the above description of representative embodiments ofthe disclosure, readily appreciate that many modifications, additions,substitutions, deletions, and other changes may be made to the specificembodiments, and such changes are contemplated by the principles of thisdisclosure. For example, structures disclosed as being separately formedcan, in other examples, be integrally formed and vice versa.Accordingly, the foregoing detailed description is to be clearlyunderstood as being given by way of illustration and example only, thespirit and scope of the invention being limited solely by the appendedclaims and their equivalents.

What is claimed is:
 1. A method of controlling flow in a subterraneanwell, the method comprising: introducing a device into the well, thedevice comprising a plurality of fibers extending outwardly from a body,wherein the fibers are joined together and form one or more linesextending outwardly from the body; conveying the device by flow in thewell; and a material of the body engaging an opening in the well anddegrading in the well in response to at least one of the groupconsisting of: passage of a predetermined period of time in the well,exposure to a predetermined temperature in the well, exposure to apredetermined fluid in the well, exposure to radiation in the well andexposure to a predetermined chemical composition in the well.
 2. Themethod of claim 1, wherein the opening comprises a perforation.
 3. Themethod of claim 1, wherein the body prevents flow through the opening.4. The method of claim 1, wherein the lines comprise one or more ropes.5. The method of claim 1, wherein the body comprises at least one knot.6. The method of claim 1, further comprising deploying the device intothe well after fracturing a formation zone.
 7. A system for use with awell, the system comprising: a flow conveyed device conveyed through atubular string by flow in the tubular string; the flow conveyed devicecomprising a body with a plurality of fibers extending outwardly fromthe body, wherein the fibers are joined together and form one or morelines extending outwardly from the body; and wherein a material of thebody engages an opening in the well and degrades in the well in responseto at least one of the group consisting of: passage of a predeterminedperiod of time in the well, exposure to a predetermined temperature inthe well, exposure to a predetermined fluid in the well, exposure toradiation in the well and exposure to a predetermined chemicalcomposition in the well.
 8. The system of claim 7, wherein the flowconveyed device engages the opening in a sidewall of the tubular string.9. The system of claim 8, wherein at least a portion of the fibers areconveyed into the opening by flow through the opening.
 10. The system ofclaim 8, wherein the body extends across and seals off the opening. 11.The system of claim 8, wherein the opening comprises a perforation. 12.The system of claim 7, wherein the body comprises at least one knot. 13.The system of claim 7, wherein the lines comprise ropes.